Powertrain, generic (extended)

P21E5 Cylinder 5 Injector B Circuit High

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P21E5 means the cylinder 5 B injector circuit is pulled toward supply voltage. GM documents it for the LT5 V8 of the 2019 Corvette ZR1: the FICM looks at the low side of that injector while its driver is off and treats 0.5 Ohm or less toward power as a short. The test needs a running engine and at least 11 V at the powertrain relay, runs continuously and sets a Type A fault. A low side held at supply potential can never be switched to ground, so the injector stays closed. On this engine the port injectors were added mainly to supply extra fuel under boost, so a dead unit tends to show at high load, where cylinder 5 may run lean. The low-side counterpart is P21E4; the A injector of the same cylinder reports P0274 for the same fault type.

Likely causes

Low-side wire of the cylinder 5 B injector shorted to a supply wire

Supply and control wire of the injector bridged in the harness

Injector coil shorted across its terminals

Damaged output stage in the injection control module

Symptoms

Check engine light on
Cylinder 5 lean or hesitant at full load
Part-load driving often feels normal

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–900

Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injectorinjector wiringengine control module

References: gsi.ext.gm.com, lsxmag.com, law.cornell.edu.